Some personal watercraft are equipped with an engine including a supercharging device such as a turbocharger or a supercharger.
Since the supercharging device is configured to compress air taken in from outside and supply the compressed air to a throttle device such as a throttle body, it generates a compression heat. If the air to be mixed with a fuel has a high temperature, then density of the air decreases, degrading engine performance. Accordingly, in order to cool the high-temperature air, an intercooler is disposed in close proximity to and downstream of the supercharging device.
However, if the intercooler is mounted in a limited internal space of a body of the watercraft, its size cannot be increased. Also, since an internal space of the body of the watercraft which is suitable in size to accommodate the intercooler is distant from a water jet pump, lengthy piping for the intercooler is needed, reducing cooling efficiency of the intercooler.